In the past, the demands on protective equipment against laser radiation in laser machining was increased, which was in particular the case as the result of the increased beam qualities and power densities achievable with fiber lasers and disc lasers.
A distinction is made between passive protective equipment and active protective equipment in this respect. With passive protective equipment, changes in or the destruction of materials are registered which occur as a result of the energy conversion into heat. In this respect, as a rule, penetration of wall elements provided for this purpose can also occur. As a rule, only a visual examination takes place in this respect subsequent to a machining with laser radiation which has to be carried out at more or less wide time intervals, which causes a correspondingly high effort and/or expense and no 100% security can be ensured.
Sufficiently secure protective walls and required support constructions therefore have to be manufactured with a high and cost-intensive use of material.
However, different active protective equipment is also known which is based on different principles. Optical systems are thus known with which specific changes such as gas formation can be detected. Another possibility is the detection of a change in an internal pressure or in a leak in or from hollow spaces which can occur with a double-wall design. It is obvious in this respect that the leak tightness is in particular problematic when an underpressure is present in such hollow spaces or when a fluid is contained in them.
Protective equipment is known from DE 36 38 874 C2 and DE 89 08 806 U1 in which electrical conductors are formed between layers and through which an electrical current flow takes place. If such an electrical conductor is parted as a consequence of melting, electrical current can no longer flow, which should then result in a deactivation of the laser. It is very complex and/or expensive in this respect to form the electrical conductors and in so doing accepting losses which are as small as possible. Even if the electrical conductors are designed in meandering form, gaps, that is, regions in which no electrical conductor is present, cannot be avoided, which is also critical with small beam cross-sections of high-power lasers which on incidence do not cause a parting of such an electrical conductor with sufficient security.
After parting an electrical conductor, this system is no longer operable and the security is only present again after replacement or complex and/or expensive repair.
A destruction of the protective equipment is necessary to determine a danger in all known active protective equipment.